利用电子万能试验机对4种典型煤种的煤块进行单轴压缩破碎实验,并用高速摄像仪记录破碎过程中煤块表面结构演化的图像,对破碎特性和细观力学特性演变开展研究。结果表明,单轴应力载荷下煤块呈现出以沿纵向主裂隙劈裂破坏为主的组合破坏形式。同煤种煤块的力学特性呈现出较明显的各向异性,这是由于煤块内部孔隙、裂隙等缺陷分布的不均匀性;不同煤种之间表现出整体差异性,受煤种组分、孔隙结构、孔径分布、变质程度等内在因素影响。微米级孔隙的孔径大小、含量与破碎过程力学特性有明显关联。孔隙率越大,孔径越大,孔隙含量越高,弹性模量与抗压强度越低。应力-应变曲线的压密段长短受样品孔隙率及煤层堆积方向与受载方向的影响。应力-应变曲线的峰值波动现象主要由其内部孔隙并合所造成。

Sample cubes from 4 typical types of coal were tested under uniaxial compression with an electronic univer- sal testing machine. The images of their surface structure evolution were recorded by a high-speed camera. The fracture characteristics and meso-mechanical properties evolution of coal cubes under uniaxial compression was investigated. It is shown that coal cubes present an integrated collapse mode predominated by cleavage along major axial fissures. Me- chanical properties shown diversities for cubes of the same coal type,which is resulted from the inhomogeneity of the internal gaps and fissures. It is also varied with different coal types,affected by inherent factors,such as composition, pore structure,pore size distribution and coal grades. Relationship with mechanical properties of coal cubes during compression was obvious for micrometer-scale fissures with their pore diameter and concentration. Elasticity modulus and strength of compression reduced with the increase of porosity,fissures diameter and fraction. The length of the ini- tial consolidation stage in the strain-stress curve was affected by porosity and directions of coal seam and loading while the peak fluctuation was related to the coalescence of the internal cracks.